Mount Waialeale, Hawaiian Wai‘ale‘ale, peak, central Kauai island, Hawaii, U.S. Waialeale (Hawaiian: “Rippling Water”), with an elevation of 5,148 feet (1,569 metres), is a dissected (eroded) dome. It is part of a central mountain mass that includes Kawaikini (5,243 feet [1,598 metres]), the island’s highest peak, immediately south. Waialeale is located at the southeastern edge of an extinct caldera that is now a plateau called Alakai Swamp. Shrouded in clouds, Waialeale is one of the world’s wettest spots, averaging some 450 inches (11,430 mm) of rainfall annually. In 1982, 666 inches (16,916 mm) of rain were recorded on the peak, establishing an official record. Only a few miles away, however, the amount of rain drops dramatically to only 10 inches (250 mm) a year.

Deep faulting and water erosion have carved canyons in the mountain’s flanks. Three valleys radiate northward: Wainiha, Lumaha‘i, and Hanalei. To the west of Mount Waialeale is Waimea Canyon—Hawaii’s “Little Grand Canyon,” or the “Grand Canyon of the Pacific.” The focus of a nearly 1,900-acre (750-hectare) state park, Waimea Canyon is some 16 miles (26 km) long and 1 to 2 miles (1.6 to 3.2 km) wide and is as much as 3,600 feet (1,100 metres) deep. Precipitation at Mount Waialeale supplies numerous waterfalls (the largest of which is the 800-foot [245-metre] cascade of Waipo‘o Falls), sending down rushing streams on all sides to feed the only navigable rivers in the state. The main rivers are the Waimea, Wailua, Makaweli, and Hanapepe.

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Rainfall variations throughout the state are dramatic. Mount Waialeale, on the island of Kauai, is often called the wettest spot on Earth, with an annual average rainfall of about 450 inches (11,430 mm). The driest area of the state is at Kawaihae, on the island of Hawaii, where the average annual rainfall is only about 9 inches (220 mm). The average yearly rainfall in Honolulu is 23 inches...

...Hawaiian islands, it is also the most verdant and one of the most scenic and is known as the Garden Isle; the name Kauai is of uncertain origin. The nearly circular island is dominated by Mount Waialeale, rising to 5,243 feet (1,598 metres) at the island’s centre. The mountain slopes are dissected by fertile valleys and deep fissures, and the island is fringed in coastal areas by marginal...

Mount Waialeale, Hawaii, with a 20-year annual average of 11,700 mm (460 inches) from tropical easterlies, is the wettest known point on the Earth. The nearest competitor is Cherrapunji, Meghālaya, with an annual average of 11,430 mm from the moist tropical monsoon. Less than 250 mm and more than 1,500 mm per year represent approximate extremes of rainfall for all of the continents....